#include <bits/stdc++.h>

using i64 = long long;

constexpr i64 inf = 1e18;

struct Node {
    std::array<int, 26> nx{};
    i64 val = inf;
};

void solve() {
    int n, k;
    std::cin >> n >> k;

    std::vector<std::string> s(n);
    for (int i = 0; i < n; ++i) {
        std::cin >> s[i];
    }

    std::string t;
    std::cin >> t;

    std::vector<i64> mn(k, inf);
    for (int i = 0; i < n; ++i) {
        int len = int(s[i].size());
        mn[len % k] = std::min<i64>(mn[len % k], len + k);
    }

    std::vector<i64> d(k, inf);
    d[0] = 0;
    for (int i = 1; i < k; ++i) {
        if (mn[i] == inf) {
            continue;
        }
        int g = std::__gcd(i, k);
        for (int j = 0; j < g; ++j) {
            for (int x = 0; x < k / g * 2; ++x) {
                int a = (x * i + j) % k, b = (a + i) % k;
                d[b] = std::min(d[b], d[a] + mn[i]);
            }
        }
    }

    std::vector<Node> trie(1);
    for (int i = 0; i < n; ++i) {
        int u = 0;
        for (int j = 0; j < int(s[i].size()); ++j) {
            int c = s[i][j] - 'a';
            if (!trie[u].nx[c]) {
                trie[u].nx[c] = int(trie.size());
                trie.emplace_back();
            }
            u = trie[u].nx[c];
            int len = s[i].size() - j - 1;
            trie[u].val = std::min(trie[u].val, k + len + d[(k - len % k) % k]);
        }
    }

    std::vector<i64> f(t.size() + 1, inf);
    f[0] = 0;
    for (int i = 0; i < int(t.size()); ++i) {
        int u = 0;
        for (int j = i; j < int(t.size()); ++j) {
            int c = t[j] - 'a';
            if (!trie[u].nx[c]) {
                break;
            }
            u = trie[u].nx[c];
            f[j + 1] = std::min(f[j + 1], f[i] + trie[u].val);
        }
    }

    i64 ans = f[t.size()];
    if (ans == inf) {
        ans = -1;
    } else {
        ans /= k;
    }
    std::cout << ans << "\n";
}

int main() {
    std::cin.tie(nullptr)->sync_with_stdio(false);

    int t;
    std::cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}